1. Field of the Invention
The present invention relates to a pattern generator and a test apparatus, particularly relates to a pattern generator and a test apparatus for testing an electronic device.
2. Related Art
Generally, a pattern generator is used for a test apparatus for testing an electronic device. The pattern generator generates test patterns being input signals for testing electronic devices, which are inputted into an electronic device. The pattern generator generates a test pattern from pattern data and sequence data.
The pattern generator includes a memory for storing a group of pattern data and a group of sequence data in the execution order and a cache memory for sequentially reading the pattern data and the sequence data from the memory and storing the same. The sequence data is a group of instructions on indicating the order of outputting the pattern data to generate a test pattern, which is composed of a jump instruction and a loop instruction and so on.
The pattern generator sequentially reads the pattern data and the sequence data from the memory and stores the same in the cache memory. The pattern generator also generates a test pattern from the pattern data stored in the cache memory based on the group of instructions of the sequence data stored in the cache memory.
When an instruction to be jumped to the addresses of the sequence data and the pattern data which are not stored in the cache memory is detected in the group of the instructions of the sequence data, the pattern generator reads from the sequence data and the pattern data corresponding to the addresses and stores the same in the cache memory.
Therefore, when the sequence data and the pattern data are read from the memory, a reading time occurs so that a latency time occurs in generating of a pattern. Additionally, when a function test and a scan test of an electronic device is executed, it has been necessary to store the data for the function test and the data for the scan test in contiguous address spaces on the memory in the execution order. Therefore, when the data for the scan test will be used multiple times, a plurality of same data should be stored in the memory, so that a mass memory is required.